Renography with captopril. Changes in a patient with hypertension and unilateral renal artery stenosis.

In a 56-year-old man with severe familial hypertension and unilateral renal artery stenosis, captopril induced striking changes in the renograms of the affected kidney. After injection of orthoiodohippurate sodium I 131, the uptake phase was unchanged but the later curve showed continuous accumulation. In contrast, the uptake of technetium Tc 99m diethylenetriamine pentracetic acid was abolished. These changes are compatible with a cessation of filtration and maintenance of renal blood flow. After balloon dilatation of the stenosis, the blood pressure became lower, and these changes could no longer be demonstrated. The captopril renogram may provide useful information on the dependency of hypertension on unilateral renal artery stenosis.

The place of renal scintigraphy in the diagnosis of renal artery stenosis. Fifteen years of clinical experience.

BACKGROUND: Renal scintigraphy with radiolabeled pentetic acid (diethylenetriamine pentaacetic acid [DTPA]) or, more recently, mertiatide (mercaptoacetyltriglycine [MAG3]), with or without captopril challenge, is widely recommended as a diagnostic test for renal artery stenosis. OBJECTIVES: To address (1) whether the diagnostic accuracy has been improved by the use of captopril and the introduction of mertiatide and (2) whether a renal scan that shows abnormalities is a useful criterion to select patients for renal arteriography. PATIENTS AND METHODS: A standard diagnostic protocol, using both scintigraphy and arteriography, was followed in 505 consecutive high-risk hypertensive patients who were evaluated for renovascular hypertension at the University Hospital Dijkzigt, Rotterdam, the Netherlands, from 1978 to 1992. RESULTS: Renal artery stenosis (> or = 50%) was present in 263 patients. When the single-kidney fractional uptake was used as a diagnostic criterion, a specificity of 0.90 was obtained at a cutoff value of 35% for the worst kidney in scintigraphy using pentetic acid without captopril challenge (n = 225) and at a cutoff value of 37% after captopril challenge (n = 280). This was associated with sensitivity levels of 0.65 and 0.68, respectively. The difference between the uptake of pentetic acid with and without captopril challenge in the 85 patients who were studied under both circumstances was no more accurate as a predictor of renal artery stenosis. In the 93 patients who were studied with mertiatide as well as with pentetic acid, both after captopril challenge, the diagnostic accuracy was no better with mertiatide than with pentetic acid; mertiatide failed to offer any advantage not only when the single-kidney fractional uptake was used as a criterion, but also with the use of other scintigraphic parameters (eg, time to peak, time to pyelum, overall shape of renographic curve, and kidney size). CONCLUSIONS: The diagnostic accuracy of renal scintigraphy has not been improved by the introduction of mertiatide or by the use of captopril. The usefulness of scintigraphy as a diagnostic test for the presence of renal artery stenosis remains questionable. The physician will always confront either a substantial number of arteriograms that do not show abnormalities when renal scintigraphy is omitted as a screening step or a substantial number of missed diagnoses when a renal scan that shows abnormalities is used as a prerequisite for arteriography.

Renovascular hypertension identified by captopril-induced changes in the renogram.

Radioisotope renography was performed in 21 patients with hypertension and unilateral renal artery stenosis with and without premedication with 25 mg of captopril, and the results were compared with the effect of percutaneous transluminal angioplasty on the blood pressure, assessed 6 weeks after angioplasty. Angioplasty caused a considerable decrease in blood pressure in 15 of the 21 patients. In 12 of these 15 patients, captopril induced changes in the time-activity curves of the affected kidney only, suggesting deterioration of the excretory function of that kidney, while the function of the contralateral kidney remained normal. After angioplasty the asymmetry in the time-activity curves diminished despite identical pretreatment with captopril. Such captopril-induced unilateral impairment of the renal function was not seen in the six patients with unilateral renal artery stenosis whose blood pressure did not change after percutaneous transluminal angioplasty or in 13 patients with hypertension and normal renal arteries. The functional impairment of the affected kidneys was characterized by a decrease of 99mTc-diethylenetriamine pentaacetic acid uptake and a delay of 131I-hippurate excretion, while the 131I-hippurate uptake remained unaffected. These data are in agreement with a reduced glomerular filtration rate and diuresis during preservation of the renal blood flow, changes that can be expected after converting enzyme inhibition in a kidney with low perfusion and an active, renin-mediated autoregulation of the glomerular filtration rate. These data suggest that functional captopril-induced unilateral changes, shown by split renal function studies with noninvasive gamma camera scintigraphy, can be used as a diagnostic test for renovascular hypertension caused by unilateral renal artery stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)

In vivo somatostatin receptor imaging in medullary thyroid carcinoma.

Using in vivo scintigraphy with the 111In-labeled somatostatin analog octreotide, tumor localizations were demonstrated in 11 of 17 patients (65%) with medullary thyroid carcinoma (MTC). Tumor localizations in the liver in 7 patients, and in the thyroid in 1 patient were not detected on octreotide scintigraphy, most probably because of normal uptake of labeled octreotide in these organs. Specific somatostatin receptors were demonstrated in vitro on all 5 investigated tumors which had also been visualized in vivo, as well as on 1 tumor that was not. Immunohistochemically, somatostatin was present in 1 of 6 tumors that were visualized in vivo, and in neither of 2 tumors that were not. The ratio of serum calcitonin over carcino-embryonic antigen concentrations was significantly higher in patients whose MTCs were visualized during octreotide scintigraphy than in those whose tumors were not. We have formed the following conclusions: 1) In the majority of patients with metastatic MTC, tumor sites can be visualized using octreotide scintigraphy, although this technique is insensitive in detecting liver metastases or intrathyroidal tumor; 2) The visualization of MTC during in vivo somatostatin receptor imaging correlates with the in vitro presence of somatostatin receptors; 3) The immunohistochemical presence of somatostatin in the tumor does not seem to influence the outcome of in vivo somatostatin receptor imaging; and 4) Higher serum calcitonin over carcino-embryonic antigen ratios in patients whose MTC is visualized during octreotide scintigraphy might imply that somatostatin receptors are present on more differentiated MTC.

[111In-DTPA-D-Phe1] octreotide scintigraphy in thyroidal and orbital Graves' disease: a parameter for disease activity?

Visualization of malignant lymphomas and granulomatous disease is possible by [111In-DTPA-D-Phe1]octreotide scintigraphy through binding of the radioligand to somatostatin receptors on activated leukocytes. Because thyroidal and orbital tissues are infiltrated by activated leukocytes in Graves' disease, a cross-sectional study to visualize disease activity with [111In-DTPA-D-Phe1]octreotide scintigraphy was performed. A correlation between thyroidal [111In-DTPA-D-Phe1]octreotide accumulation and free T4 (disease expression) and thyroid binding-inhibiting immunoglobulins (disease activity) is present in untreated hyperthyroid Graves' disease. There is also a correlation between orbital [111In-DTPA-D-Phe1]octreotide uptake and the clinical activity score (disease activity) and total eye score (disease expression), respectively, in Graves' orbitopathy. Visualization of thyroidal and orbital Graves' disease is feasible, but further investigation is necessary to establish the role of [111In-DTPA-D-Phe1]octreotide scintigraphy in representing disease activity and expression and in predicting therapeutical outcome.

Somatostatin receptor scintigraphy: its value in tumor localization in patients with Cushing's syndrome caused by ectopic corticotropin or corticotropin-releasing hormone secretion.

PURPOSE: To assess the feasibility of somatostatin receptor scintigraphy for patients with Cushing's syndrome caused by tumors secreting ectopic corticotropin or corticotropin-releasing hormone (CRH). PATIENTS AND METHODS: Ten patients with Cushing's syndrome, nine with ectopic corticotropin-secreting tumors and one with a CRH-secreting tumor, were consecutively studied. For comparison purposes, eight patients with corticotropin-secreting pituitary tumors and one patient with an autonomous adrenal adenoma were investigated. In vivo tumor localization was performed for all patients using a radionuclide-coupled somatostatin analog. The results obtained with this technique were compared with those obtained with conventional imaging techniques. For some patients, the clinical effects of octreotide therapy were evaluated. RESULTS: Somatostatin analog scintigraphy successfully identified the primary ectopic corticotropin-secreting and CRH-secreting tumors or their metastases, or both, in 8 of 10 patients; in 2 patients with corticotropin-secreting bronchial carcinoids, the tumors could not be visualized. Normal scans were obtained for the 8 patients with corticotropin-secreting pituitary tumors and the one patient with an adrenal adenoma. CONCLUSION: Somatostatin analog scintigraphy can be included as a diagnostic step in the workup of Cushing's syndrome patients with a suspected ectopic corticotropin-secreting tumor or a CRH-secreting tumor.

Radioiodinated somatostatin analog scintigraphy in small-cell lung cancer.

Somatostatin receptors have been characterized on biopsy specimens from small-cell lung carcinoma (SCLC) and on cultured human SCLC cells. We recently described the in vivo visualization of various somatostatin receptor-positive tumors, such as carcinoids and endocrine pancreatic tumors, after injection of 123I-Tyr-3-octreotide, a radiolabeled somatostatin analog. In the present study, this imaging procedure using 123I-Tyr-3-octreotide is reported in 11 patients with lung tumors. In five of eight patients with SCLC (63%), we were able to demonstrate tumor deposits using 123I-Tyr-3-octreotide scintigraphy. Unexpected metastases were found in two patients. In one of three patients with SCLC in whom tumor was not visualized, nonvisualization may have been caused by tumor necrosis and recent radiotherapy. In one of two patients with malignant small-cell tumors as described by Askin, the neoplasm was visualized. Like SCLC, these tumors are thought to derive from neuroendocrine cells. In one patient, a squamous-cell carcinoma and a bronchial adenoma were not visualized. We conclude that in the majority of patients with SCLC, the tumor and its metastases can be visualized using 123I-Tyr-3-octreotide scintigraphy. However, the value of this new technique in terms of specificity and sensitivity requires further studies in a larger group of patients.

Somatostatin receptor scintigraphy in the initial staging of low-grade non-Hodgkin's lymphomas.

UNLABELLED: In this prospective study, somatostatin receptor (SS-R) scintigraphy was compared with conventional staging procedures for the initial staging of patients with low-grade non-Hodgkin's lymphoma (NHL). METHODS: Fifty consecutive untreated patients with low-grade NHL underwent SS-R scintigraphy as part of their initial staging. Planar images were obtained 24 and 48 h after intravenous injection of 220 MBq (111)In-pentetreotide. SPECT images of the upper abdomen were obtained from all patients. SS-R scans were evaluated blindly without knowledge of the results of the conventional staging methods. SS-R scintigraphy findings were compared with the results of physical and radiologic examinations. RESULTS: SS-R scintigraphy findings were positive in 42 of 50 patients (84%). In 10 patients (20%), the SS-R scan revealed new lesions that had not been revealed by conventional staging procedures. These 10 patients were all upgraded to a higher stage. Consequently, the treatment plan would have been altered in 5 patients (10%). However, in 19 patients (38%), lesions apparent after conventional staging methods were missed by SS-R scintigraphy. The sensitivity of SS-R scintigraphy varied from 62% for supradiaphragmatic lesions to 44% for infradiaphragmatic lesions. The specificity of SS-R scintigraphy was high (98%-100%). In comparison with CT scanning and sonography, SS-R scintigraphy is inferior for the visualization of NHL lesions in the thorax and abdomen. CONCLUSION: Although SS-R scintigraphy findings are positive in a large proportion of patients with low-grade NHL, in most patients only part of the lesions can be visualized. Because of the limited sensitivity, we recommend SS-R scintigraphy for initial staging of patients with low-grade NHL only in selected conditions and not for the general work-up.

Dopamine-producing paraganglioma not visualized by iodine-123-MIBG scintigraphy.

A patient with an aorticopulmonary paraganglioma was found to have normal plasma norepinephrine and epinephrine levels and elevated dopamine levels. Iodine-123-MIBG scintigraphy did not visualize this tumor. The same finding on a negative MIBG scan in two patients with exclusively dopamine-secreting chemodectomas has been previously reported. In our patient, [111In-DTPA-D-Phe1]-octreotide scintigraphy proved to be an effective imaging technique.

Somatostatin receptor scintigraphy with indium-111-DTPA-D-Phe-1-octreotide in man: metabolism, dosimetry and comparison with iodine-123-Tyr-3-octreotide.

Scintigraphy with 123I-Tyr-3-octreotide has several major drawbacks as regards its metabolic behavior, its cumbersome preparation and the short physical half-life of the radionuclide. The use of another radiolabeled analog of somatostatin, 111In-DTPA-D-Phe-1-octreotide, has consequently been proposed. DTPA-D-Phe-1-octreotide can be radiolabeled with 111In in an easy single-step procedure. DTPA-D-Phe-1-octreotide is cleared predominantly via the kidneys. Fecal excretion of radioactivity amounts to only a few percent of the administered radioactivity. For the radiation dose to normal tissues, the most important organs are the kidneys, the spleen, the urinary bladder, the liver and the remainder of the body. The calculated effective dose equivalent is 0.08 mSv/MBq. Optimal 111In-DTPA-D-Phe-1-octreotide scintigraphic imaging of various somatostatin receptor-positive tumors was obtained 24 hr after injection. In the six patients studied, tumor localization with 123I-Tyr-3-octreotide and with 111In-DTPA-D-Phe-1-octreotide were found to be similar. However, the normal pituitary is more frequently visualized with the latter radiopharmaceutical. In conclusion, 111In-DTPA-D-Phe-1-octreotide appears to be a sensitive somatostatin receptor-positive tissue-seeking radiopharmaceutical with some remarkable advantages: easy preparation, general availability, appropriate half-life and absence of major interference in the upper abdominal region, because of its renal clearance. Therefore, 111In-DTPA-D-Phe-1-octreotide may be suitable for use in SPECT of the abdomen, which is important in the localization of small endocrine gastroenteropancreatic tumors.

Report of the Radionuclides in Nephrourology Committee for evaluation of transplanted kidney (review of techniques).

Comprehensive evaluation of renal transplants has been important in differential diagnosis of medical and surgical complications in the early post-transplantation period and in the long-term follow-up. If performed well, it yields excellent functional and good anatomic information about the graft that can be effectively used in the patient. That includes selection of patients for biopsy and for various drug regimens. This is true especially in patients with anuric acute tubular necrosis (ATN) and in patients with developing chronic rejection. Improving indices of renal function (effective renal plasma flow, uptake of tubular tracers) can indicate resolution of tubular injury (ATN) while there is still no improvement in plasma creatinine. In patients with chronic rejection, plasma creatinine increases only after approximately 30% of renal function is lost due to graft fibrosis. Early recognition of this condition could permit treatment and delay of retransplantation. The protocol recommended at the Copenhagen meeting includes a flow study, scintigram of the kidneys, prevoid and postvoid bladder image, injection site image (quality control), time/activity curves of the graft and bladder, and quantitative data of perfusion, function, and tracer transit. The flow study obtained during the initial transit of the bolus through the graft could be performed either with 99mTc mercaptoacetyltriglycine, or 99mTc diethylenetriaminepentaacetate (DTPA). Quantitative analysis of perfusion facilitates interpretation of the study during the early post-transplantation period. ATN, common in cadaver transplants, typically shows adequate perfusion. The function phase should include images and time/activity curves. Images alone are insufficient. Quantitative data such as clearance or other indices of function and indices of tracer transit are essential for correct interpretation of the results. Normal images and normal graft function reliably exclude clinically important complications. A single scintigram demonstrating prolonged tracer transit with decreased function cannot separate acute rejection and ATN. On serial studies, decline in function and poor perfusion are indicative of acute rejection. A normally appearing scintigram without cortical retention, but with low function, is consistent with chronic rejection. Pharmacological intervention to exclude obstruction (diuretic renogram) or hemodynamically significant renal artery stenosis (angiotensin converting enzyme challenge) should be used whenever indicated.

Captopril renography. Early observations and diagnostic criteria.

This article describes the methods and the interpretation of captopril renography. The essentials of the methods are the discontinuation of diuretics, the refraining from solid foods before administration of 25 mg captopril, hydration to induce diuresis, the performing of 1-min sequential images, data acquisition with frame time not exceeding 30 sec, and the calculation of the left to right ratio. In most instances data from captopril renography can be interpreted without the presence of a baseline study. Abnormalities of the sequential images and the renal curves classified as grade 2 and 3 indicate the presence of renal artery stenosis. Besides, in unilateral stenosis, captopril induced renographic abnormality can also be observed in bilateral and segmental stenosis. Interpretation based on numeric parameters probably does not increase the sensitivity. Alterations on mercaptoacetyltriglycine (MAG3) studies are identical to the alterations observed on orthoiodohippurate (OIH) studies. In severe stenosis, alterations in diethylene-triaminepentaacetic acid studies are different from those observed in OIH or MAG3 studies. Since MAG3 provides the best images, at present MAG3 is the radiopharmaceutical of choice.

Gastric emptying and postprandial symptoms after Billroth II resection.

Gastric emptying was studied in 18 symptomatic and 16 asymptomatic patients after Billroth II (BII) resection (without vagotomy) and the possible relationships between emptying and postprandial symptoms in these patients were assessed. The BII patients were compared with 20 nonoperated patients who had duodenal ulcer disease and 16 healthy subjects. Gastric emptying of two test meals (a semisolid porridge meal and a solid pancake meal) was measured with a radionuclide technique. The major difference between the BII patients and control subjects and duodenal ulcer patients was an increased rate of emptying of the semisolid meal in the first 5 minutes after meal consumption. The percentage of the meal remaining in the stomach at 5 minutes after completion was significantly less in the symptomatic (45.3% +/- 4.3%) than in the asymptomatic BII patients (79.4% +/- 2.6%). A positive correlation was demonstrated between the initial emptying rate of semisolids and the intensity of postprandial nausea (p less than 0.01), vomiting (p less than 0.05), and vasomotor symptoms (p less than 0.001). The duration of the lag phase for solid and semisolid meals was shorter in BII patients than in healthy subjects but was as short in nonoperated duodenal ulcer patients. The duration of the lag phase for solid food in the BII patients correlated positively with the score for postprandial epigastric pain (p less than 0.001). The rate of emptying of the solid meal was lower in symptomatic BII patients (28.1% +/- 3.6% per hour) than in asymptomatic patients (47.8% +/- 7.2% per hour) and correlated with the severity of postprandial fullness and nausea. The emptying of the solid meal was inversely related to the initial emptying rate of the semisolid meal (p less than 0.05). Therefore, the results of this study support the assumption that many of the postprandial symptoms occurring after BII resection reflect alterations in gastric emptying. Some of the emptying abnormalities present after BII resection may be related to duodenal ulcer disease rather than to the surgical procedure.

111In-octreotide scintigraphy in oncology.

Various tumors of neuroendocrine origin that have amine precursor uptake and decarboxylation (APUD) characteristics can be visualized in vivo after intravenous (IV) injection of the somatostatin analogue, [123I-Tyr3]-octreotide. However, the relatively short effective half-life of this compound and the high background of radioactivity in the abdomen are drawbacks to its application. Therefore, an 111In-coupled somatostatin analogue ([111In-DTPA-D-Phe1]- octreotide) was developed. This analogue is excreted mainly via the kidneys, with 90% of the dose being present in the urine 24 hours after injection. Using 111In-octreotide scintigraphy, seven of seven gastrinomas, four of seven insulinomas, one of one glucagonomas, three of three unclassified APUDomas, and none of 18 exocrine pancreatic carcinomas were visualized. Also, 19 of 19 carcinoids, 15 of 15 glomus tumors, eight of 12 medullary thyroid carcinomas, six of six small-cell lung carcinomas, four of four growth hormone-producing and six of nine clinically nonfunctioning pituitary adenomas were visualized. Apart from APUD cell-derived tumors, 111In-octreotide scintigraphy was also successfully applied in visualizing breast cancer, lymphomas, and granulomas. In 39 of 50 patients with breast carcinoma, 10 of 11 patients with non-Hodgkin's lymphomas, three of three patients with Hodgkin's disease, and eight of eight patients with sarcoidosis, tumor sites accumulated radioactivity during octreotide scintigraphy. In a considerable number of patients with carcinoids and glomus tumors, and also in patients with granulomas and lymphomas, 111In-octreotide scintigraphy showed more tumor sites than did conventional imaging techniques. The results of imaging in vivo correlated with the somatostatin-receptor status on the tumors in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

Somatostatin analogue scintigraphy. A simple and sensitive method for the in vivo visualization of Merkel cell tumors and their metastases.

BACKGROUND: Trabecular carcinomas of the skin, or Merkel cell tumors, are aggressive neoplasms that tend to occur in sun-exposed skin. These tumors frequently metastasize and, despite therapy, the number of disease-related deaths is high. Ultrastructurally and immunocytochemically, the majority of these tumors have neuroendocrine characteristics. Recently, we described the in vivo visualization of various neuroendocrine tumors after injection of a radiolabeled somatostatin analogue (octreotide). In this study, we report the results of scintigraphy with radioactive-labeled somatostatin analogues in five patients with Merkel cell tumors. OBSERVATIONS: In all four patients in whom tumor was detected using computed tomographic scanning and ultrasound, the tumor sites were also demonstrated on octreotide scintigrams. In one patient, a tumor with a diameter that was smaller than 0.5 cm could not be detected with octreotide scintigraphy, computed tomography, or ultrasound. Using octreotide scintigraphy we found presumed tumor spots in two patients that were not evident when other techniques were used. CONCLUSIONS: Octreotide scintigraphy has an equal or even greater sensitivity than computed tomography and ultrasound for detecting Merkel cell tumors and their metastases. Establishing the spread of the disease in this way may ensure an optimal choice of treatment in patients with this type of tumor.

Routine testing of liver function after biliary-enteric anastomosis has no clinical relevance.

BACKGROUND/AIMS: Patients who had a biliary-enteric anastomosis often have elevated liver function tests. The aim of this study was to investigate whether elevated liver function tests are associated with recurrent episodes of cholangitis. METHODOLOGY: Thirty-two patients, who received a biliary-enteric anatomosis for benign biliary disease were evaluated. Follow-up consisted of the patient's history, physical examination, determination of liver function tests, ultrasonography and hepatobiliary scintigraphy using 99mTc-HIDA. RESULTS: Median duration of follow-up was 45 months (range: 1-192) and liver function tests were elevated in 22 patients (69%) at some time during follow-up. Dilated intrahepatic ducts were found in 3 of 30 patients (10%), all of whom had elevated liver function tests at follow-up. Delayed passage from the liver was observed using scintigraphy in 10 (31%) of the patients. Seven patients (22%) experienced one episode of cholangitis and none experienced more than one episode. Multivariate analysis showed that male sex was an independent risk factor for elevated liver function tests (odds ratio: 10.9; P < 0.05). For cholangitis, no risk factors could be identified. CONCLUSIONS: It is concluded that elevated liver function tests are relatively common after a biliary-enteric anastomosis for benign biliary tract disease and are not predictive of the occurrence of cholangitis. We, therefore, recommend omitting routine laboratory screening for elevated liver function tests in the follow-up of a biliary-enteric anastomosis.

[Preoperative noninvasive tests for localization of enlarged parathyroid glands in 115 patients with hyperparathyroidism]. / Preoperatieve non-invasieve lokalisatieonderzoeken van vergrote bijschildklieren bij 115 patiënten met hyperparathyreoïdie.

OBJECTIVE: To evaluate results of preoperative localisation techniques in patients operated for hyperparathyroidism (HPT). SETTING: Rotterdam University Hospital. DESIGN: Retrospective study. METHOD: Results of 4 non-invasive preoperative localisation techniques in 115 patients with HPT were compared with operative findings of 116 explorations. Sensitivity and specificity were calculated for single versus multiple gland disease, primary exploration versus re-explorations and anatomical versus ectopic localisation. RESULTS: Sensitivity of preoperative ultrasound, thallium-technetium subtraction scintigraphy, computed tomography and 99mTc-sestamibi (MIBI) scanning in patients with single gland disease was 56%, 65%, 67% and 83% respectively. In multiple gland disease preoperative localisation techniques were much less successful. For MIBI scintiscanning this question remains unanswered. Specificity of all techniques was high. Success rates of preoperative localisation studies for primary operations and re-explorations were similar. Mean weight of parathyroid tumours that were missed preoperatively was lower than of successfully localised tumours. Only computed tomography and thallium-technetium scintigraphy were able to localise retrosternal parathyroid tumours. CONCLUSION: Review of the literature reveals that there is additional benefit of the preoperative localisation studies in re-exploration for HPT, in contrast to primary exploration. By combining localisation techniques more tumours are visualised. Preliminary results of MIBI scanning are favourable.

Radionuclide measurement of normal and disturbed gastric motility.

Techniques for the measurement of gastric emptying using radionuclides are reviewed as a basis for a discussion of gastric emptying tests. A new technique for the noninvasive quantitative measurement of antral motility is described, whereby measurements of redistribution of gastric contents between fundus and antrum and actual gastric emptying are obtained simultaneously. These tests provide more relevant insight into the pathophysiology of gastric motility disturbances than that previously obtained by conventional gastric emptying studies.